1. Field of the Invention
The present invention relates to a method of logging a subterranean formation penetrated by an inclined wellbore and, more particularly, to such a method whereby a logging tool is restrained within a drillstring and the formation is logged while the drillstring is withdrawn.
2. Setting of the Invention
It is well known in the art to conduct logging operations within a wellbore that penetrates at least one subterranean formation. It is further well known to conduct such operations within steeply inclined and horizontal wellbores. However, horizontal wellbores cannot be logged in conventional fashion since a logging tool assembly will not drop under its own weight on a wireline cable to the end of the 90.degree. curved portion. To conduct such operations, a logging tool is connected to an end of a flexible tubing string that is lowered/raised within the wellbore. Commercially available pipe-conveyed logging systems include Institut Francais Du Petrole "SIMPHOR," Gearhart Industries "TOOL PUSHER," Atlas "SLANT-HOLE EXPRESS" and Welex's "PLS." All of these systems are relatively complex and expensive to operate.
There is a need for a simple method of logging an inclined wellbore which does not require the use of a separate tubing string or can utilize conventional, less costly logging tools.